Ever since I learned that “if” and “when” can be used as translations for the -たら conditional form depending on the context, I have been looking for an explanation of its construction in terms of its etymology to have a proper understanding of how it works. The sources I have looked up say that it is formed from the “past tense” -た form + ら, but I have failed to find any information on this ら. Is it a classical Japanese auxiliary verb? Is the full form -たらば? Does it have anything to do with the 連体形 or attributive form of classical verb ending ～たり? Or is -たら the 仮定形 form of -た? Where does -たら come from?
Please enlighten me on this topic so that I can stop translating this expression to English and start seeing it in terms of Japanese.
3 comments
[https://www.imabi.net/theconditionals.htm](https://www.imabi.net/theconditionals.htm)
[https://www.imabi.net/tensei.htm](https://www.imabi.net/tensei.htm)
probably more in imabi, it doesn’t have good searching options but leaf thru the classical chapters and you’ll probably find what you want
た is itself a contraction of てあり/たり, much like how だ is a contraction of であり. たら is the 未然形 of たり. In classical Japanese, the conditional was used with the 未然形 instead of the 仮定系, for example なる -> ならば.
(this is all very simplified because I don’t want to go into too much details, please look into these if you want to know more: [1](https://dictionary.goo.ne.jp/word/たり/#jn-139244) [2](https://dictionary.goo.ne.jp/word/た/#jn-132183) [3](https://dictionary.goo.ne.jp/word/たら/#jn-139154) [4](https://dictionary.goo.ne.jp/word/ば/#jn-172830) [5](https://ja.wikipedia.org/wiki/活用#活用形))
I believe it’s similar to how ならば (なり+ば) became なら. But in that case both are still used. With たら, we lost たらば (たり+ば).